In order to research the mechanical response of continuously reinforced concrete pavement on foam concrete interlayer for a two-way curved arch bridge, the elliptical vehicle load is translated into the rectangular lo...In order to research the mechanical response of continuously reinforced concrete pavement on foam concrete interlayer for a two-way curved arch bridge, the elliptical vehicle load is translated into the rectangular load based on the equivalence method. Then, a three-dimensional finite element model of the whole bridge is established. The reliability of the model is verified. Additionally, the mechanical response of continuously reinforced concrete pavement under vehicle loading is analyzed. Finally, the most unfavorable loading conditions of tensile stress, shear stress and vertical displacement are determined. The results show that the most unfavorable loading condition of tensile stress, which is at the bottom of continuously reinforced concrete pavement on the two-way curved arch bridge, is changed compared with that on homogeneous foundation. The most unfavorable loading condition of shear stress at the top is also changed. However, the most unfavorable loading condition of vertical displacement remains unchanged. The tensile stress at the bottom of about 1/4 span of the longitudinal joint, the shear stress at the top of intersection of transverse and longitudinal joint, together with the vertical displacement at the central part of longitudinal joint, are taken as design indices during the structural design of continuously reinforced concrete pavement on the two-way curved arch bridge. The results are helpful for the design of continuously reinforced concrete pavement on unequal- thickness base for the two-way curved arch bridge.展开更多
针对超声速气流驱动干粉颗粒形成的缩放喷管气固两相射流,采用拉格朗日方法、气固双向耦合模型以及Shear-Stress Transport k-ω湍流模型进行数值模拟,分析了颗粒装载比、萨夫曼力和入口压力等因素对气体参数、颗粒速度以及颗粒聚集度...针对超声速气流驱动干粉颗粒形成的缩放喷管气固两相射流,采用拉格朗日方法、气固双向耦合模型以及Shear-Stress Transport k-ω湍流模型进行数值模拟,分析了颗粒装载比、萨夫曼力和入口压力等因素对气体参数、颗粒速度以及颗粒聚集度的影响。结果表明:气固双向耦合模型可以准确的分析气体与颗粒之间的相互作用。当高压气体通过缩放喷管时会产生超声速流动,从而带动颗粒作加速运动;在同一入口压力下,如果颗粒装载比较高,那么颗粒速度较小,且气体参数受颗粒的影响较大。颗粒在喷管扩张段轴线附近聚集,导致轴线到壁面附近区域内,产生沿径向向外的气流速度梯度,这可以解释萨夫曼力使轴线上气固两相的速度增大,并且在高颗粒装载比下的影响更显著的原因。不同入口压力下可能出现欠膨胀、过膨胀和完全膨胀三种不同喷管射流形态;在完全膨胀流态下,颗粒加速和气流降温的效果相对更好。研究结果可为超声速干粉灭火技术的应用提供理论支撑。展开更多
基金The Science Foundation of Ministry of Transport of the People's Republic of China(No.200731822301-7)
文摘In order to research the mechanical response of continuously reinforced concrete pavement on foam concrete interlayer for a two-way curved arch bridge, the elliptical vehicle load is translated into the rectangular load based on the equivalence method. Then, a three-dimensional finite element model of the whole bridge is established. The reliability of the model is verified. Additionally, the mechanical response of continuously reinforced concrete pavement under vehicle loading is analyzed. Finally, the most unfavorable loading conditions of tensile stress, shear stress and vertical displacement are determined. The results show that the most unfavorable loading condition of tensile stress, which is at the bottom of continuously reinforced concrete pavement on the two-way curved arch bridge, is changed compared with that on homogeneous foundation. The most unfavorable loading condition of shear stress at the top is also changed. However, the most unfavorable loading condition of vertical displacement remains unchanged. The tensile stress at the bottom of about 1/4 span of the longitudinal joint, the shear stress at the top of intersection of transverse and longitudinal joint, together with the vertical displacement at the central part of longitudinal joint, are taken as design indices during the structural design of continuously reinforced concrete pavement on the two-way curved arch bridge. The results are helpful for the design of continuously reinforced concrete pavement on unequal- thickness base for the two-way curved arch bridge.
文摘针对超声速气流驱动干粉颗粒形成的缩放喷管气固两相射流,采用拉格朗日方法、气固双向耦合模型以及Shear-Stress Transport k-ω湍流模型进行数值模拟,分析了颗粒装载比、萨夫曼力和入口压力等因素对气体参数、颗粒速度以及颗粒聚集度的影响。结果表明:气固双向耦合模型可以准确的分析气体与颗粒之间的相互作用。当高压气体通过缩放喷管时会产生超声速流动,从而带动颗粒作加速运动;在同一入口压力下,如果颗粒装载比较高,那么颗粒速度较小,且气体参数受颗粒的影响较大。颗粒在喷管扩张段轴线附近聚集,导致轴线到壁面附近区域内,产生沿径向向外的气流速度梯度,这可以解释萨夫曼力使轴线上气固两相的速度增大,并且在高颗粒装载比下的影响更显著的原因。不同入口压力下可能出现欠膨胀、过膨胀和完全膨胀三种不同喷管射流形态;在完全膨胀流态下,颗粒加速和气流降温的效果相对更好。研究结果可为超声速干粉灭火技术的应用提供理论支撑。
